1. Field of the Invention
This invention relates to an apparatus and method for determining the osmolarity/specific gravity of a solution and, more particularly, through a novel system for matching the osmolarity of an unknown solution with one of a plurality of discrete test solutions of known concentrations encapsulated with a semipermeable membrane.
2. The Prior Art
The determination of the osmolarity and/or specific gravity of a sample solution is an important analytical procedure for many applications. Various methods and apparatus for measuring osmolarity and/or specific gravity of a solution are commercially available and well-known in the art. Available apparatus include hydrometers, gravitometers, pycnometers, urinometers, and osmometers. While these devices are generally conceded to be accurate, they also tend to be expensive, bulky, and generally require a substantial investment in operator time, support equipment, supplies, calibration, and, in certain instances, a relatively large liquid sample volume.
A recent prior art device is disclosed in U.S. Pat. No. 4,015,462 issued Apr. 5, 1977 and relates to a system incorporating a plurality of osmotically fragile, semipermeable membrane capsules having a predetermined specific gravity and containing a combination of solute and coloring substance. Contact between the test system and a liquid having a specific gravity lower than the specific gravity of the test system produces the hydrostatic pressure within the capsules causing the capsules to break and release the coloring substance. The density of the color produced by the release of the coloring substance is inversely related to and indicative of the specific gravity of the liquid contacted. This test system requires the evaluation of the intensity of the color with a color standard in order to determine specific gravity and is, therefore, subject to variation depending upon the particular individual making the intensity determination.
In view of the foregoing, it would be an advancement in the art to provide a novel test apparatus and method for determining the osmolarity/specific gravity of a solution that is accurate, easily readable even by an unskilled operator, and rapid without the requirement for expensive, bulky or otherwise difficult to calibrate equipment, and the like. It would also be an advancement in the art to provide a single-use test apparatus and method for determining the osmolarity/specific gravity of a solution wherein the apparatus is inexpensive and readily disposable. Such an invention is disclosed and claimed herein.